I'm an FO with Baby and can honestly say that I personally have not suffered any of the roster disruption that has been highlighted here. I've only done 90 hours in a 28 day period once and that was when I was line training, which was exactly what I needed at that stage. Since then I've probably averaged about 60 hours per month. Last month was 48 and that was with no leave. I think we must be over crewed with FOs as I hardly ever get called on standby either. As for 6 sector days, I only seem to average 1 per roster.
Its not the same for the Captains though; every one I've flown with seems to suffer a lot of roster changes and always seem to get called on Standbys.
It's not perfect but for me its not been as bad as the experiences of the previous posters, the money is good, the crews are great and the route structure gives a nice variety of flying.